Synovial fluid alpha-defensins in Lyme arthritis-a useful marker.

Lyme arthritis, one of the possible late manifestations of Lyme borreliosis, predominantly affects the supporting joints and in adults most often occurs in the form of monoarthritis of the knee. Early diagnosis is based on clinical findings and serology. PCR detection of Borrelia in synovial fluid has become an integral part of the laboratory testing algorithm. The clinical presentation and inflammatory markers in Lyme arthritis can resemble septic arthritis. Determining the levels of alpha-defensins (human neutrophil peptide (HNP 1-3)) in synovial fluid by liquid chromatography is a highly sensitive method revealing the presence of inflammatory process. Between 2020 and 2022, we examined eleven patients with Lyme arthritis of the knee. We measured levels of HNP 1-3 from synovial fluid by HPLC in patients, and we compared it with the corresponding C-reactive protein (CRP) levels in paired serum samples. In patients diagnosed with Lyme arthritis, HNP 1-3 levels in synovial fluid ranged from 2.5 to 261 mg/L, with a median of 46.5 mg/L. Average serum CRP was 43 mg/L. The results show that elevated HNP 1-3 can be consistent with not only septic arthritis or systemic disease, but also with Lyme arthritis, especially in patients with negative culture and 16S PCR from synovial fluid. Final diagnosis must be verified by examination for anti-Borrelia antibodies from serum and synovial fluid. The aim of this work is to introduce an HPLC method for the determination of alpha-defensins as one of the possible diagnostic markers.

Acidity Is an Excellent Marker of Infection in Hip and Knee Arthroplasty.

BACKGROUND: The diagnosis of joint replacement infection is a difficult clinical challenge that often occurs when the implant cannot be salvaged. We hypothesize that the pH value of synovial fluid could be an important indicator of the inflammatory status of the joint. However, in the literature, there is a lack of data on the pH changes in hip and knee joint replacements and their relation to infection and implant failure. In this study, we aimed to measure the pH levels of synovial fluid in patients with hip and knee joint replacements. We also investigated the potential of pH measurement as a diagnostic tool for joint replacement infection. In this study, we recorded the pH values to be 7.55 and 7.46 in patients where Pseudomonas aeruginosa was identified as the cause of the prosthetic joint infection. We attribute this to the different environments created by this specific bacterium. In other cases where the pH was higher, chronic mitigated infections were diagnosed, caused by strains of Staphylococcus aureus, Streptococcus agalactiase, and coagulase negative staphylococcus. MATERIALS AND METHODS: In our cohort of 155 patients with implanted hip (THA; n = 85) or knee (TKA; n = 70) joint replacements, we conducted a prospective study with a pH measurement. Out of the whole cohort, 44 patients had confirmed joint replacement infection (28.4%) (44/155). In 111 patients, infection was ruled out (71.6%) (111/155). Joint replacement infection was classified according to the criteria of the Musculoskeletal Infection Society (MSIS) from 2018. Based on the measured values, we determined the cut-off level for the probability of ongoing inflammation. We also determined the sensitivity and specificity of the measurement. RESULTS: The group of patients with infection (n = 44) had a significantly lower synovial fluid pH (pH = 6.98 ± 0.48) than the group of patients with no infection (n = 111, pH = 7.82 ± 0.29, p < 0.001). The corresponding median pH values were 7.08 for the patients with infection and 7.83 for the patients with no infection. When we determined the cut-off level of pH 7.4, the sensitivity level of infected replacements was 88.6%, and the specificity level of the measurement was 95.5%. The predictive value of a positive test was 88.6%, and the predictive value of a negative test was 95.5%. CONCLUSIONS: Our results confirm that it is appropriate to include a pH measurement in the diagnostic spectrum of hip and knee replacements. This diagnostic approach has the potential to provide continuous in vivo feedback, facilitated by specialized biosensors. The advantage of this method is the future incorporation of a pH-detecting sensor into intelligent knee and hip replacements that will assess pH levels over time. By integrating these biosensors into intelligent implants, the early detection of joint replacement infections could be achieved, enhancing proactive intervention strategies.

Antimicrobial peptide in polymethylmethacrylate bone cement as a prophylaxis of infectious complications in orthopedics-an experiment in a murine model.

Polymethylmethacrylate (PMMA) bone cement mixed with antibiotics is used in orthopedic surgery to cope with implant-related infections which are typically associated with the formation of bacterial biofilms. Taking into account the growing bacterial resistance to current antibiotics, we examined here the efficacy of a selected antimicrobial peptide (AMP) mixed into the bone cement to inhibit bacterial adhesion and the consequent biofilm formation on its surface. In particular, we followed the formation of bacterial biofilms of methicillin-resistant Staphylococcus aureus (MRSA) on implants made from PMMA bone cement loaded with AMP composed of 12 amino acid residues. This was evaluated by CFU counting of bacteria released by sonication from the biofilms formed on their surfaces after these implants were retrieved from the infected murine femoral canals. The AMP loaded in these model implants prevented adhesion of MRSA and the subsequent formation of MRSA biofilm on the surfaces of more than 80% of these implants, whereas biofilms did form on control implants made from the plain cement. The results of our experiments performed in the murine femoral canal indicate the potential for this murine osteomyelitis model to mimic actual operations in orthopedics.

High-Performance Liquid Chromatography as a Novel Method for the Determination of α-Defensins in Synovial Fluid for Diagnosis of Orthopedic Infections.

The α-defensins (AD) present in synovial fluid have been regarded as constituting the most accurate periprosthetic joint infection (PJI) biomarker. The methods most commonly used for estimating AD as a biomarker are the qualitative Synovasure® PJI tests, based on the technique of lateral flow, and quantitative enzyme-linked immunosorbent assay (ELISA). Here, we propose a novel test based on detecting α-defensins in synovial fluid by high-performance liquid chromatography (HPLC). Synovial fluid was collected from 157 patients diagnosed with PJI, infectious arthritis (IA), arthrosis, reactive arthritis, and rheumatoid arthritis. AD concentrations in the fluid were determined by HPLC, and these same samples were used for additional diagnostic analyses. The results were statistically processed to calculate cutoff concentrations for PJI and IA. HPLC testing showed a sensitivity of 94% and a specificity of 92% for diagnosis of PJI, and a sensitivity of 97% and a specificity of 87% for diagnosis of IA. Using HPLC, we detected in synovial fluid a combination of three α-defensins: human neutrophil peptides HNP1, HNP2, and HNP3. All measured AD concentration values shown in this work refer to the sum of these three individual concentrations. Our study shows that the HPLC method meets the conditions for measuring precise concentrations of the sum of AD and can be recommended as part of a diagnostic array for PJI and IA diagnostics. By this method, we have verified that higher levels of AD in synovial fluid can also be seen in rheumatoid illnesses, crystal arthropathies, and reactive arthritis.

Vancomycin and its crystalline degradation products released from bone grafts and different types of bone cement.

Vancomycin is often used in orthopedic surgery as a local prophylaxis of bacterial infection. The aim of this work was to compare the release of vancomycin and its biologically inactive crystalline degradation products (CDP-1) during in vitro experiments from different types of local antibiotic delivery systems (bone grafts and bone cements). The concentrations of vancomycin and its crystalline degradation products were determined by high-performance liquid chromatography. Each experiment was performed in a phosphate buffer solution over 21 days. Morselized bone grafts, synthetic bone cements Palacos and Copal, and synthetic bone grafts were tested as local carriers of vancomycin. The highest concentration approximately 670 mg/L of vancomycin was released from synthetic bone grafts Actifuse. Even after 21 days, the concentration of vancomycin was still above the minimum inhibitory concentration (MIC). The maximum concentration of vancomycin released in two experiments with human bone grafts exceeded 600 mg/L during the first day and was still above MIC level 21 days later when the experiment was concluded. By comparing the synthetic bone cements Palacos and Copal, Copal had the average maximum concentration of only 32.4 mg/L and Palacos 35.7 mg/L. The concentration of vancomycin fell below the MIC for vancomycin-resistant Staphylococcus aureus (VRSA) on the seventh day with Palacos and the ninth day with Copal. This study showed the insufficient concentration of released vancomycin from synthetic bone cements at the end of the experiment. For improvement of local prophylaxis, it would be beneficial to increase the amount of vancomycin in bone cements.

Testing the efficacy of antimicrobial peptides in the topical treatment of induced osteomyelitis in rats.

Joint replacement infections and osteomyelitis are among the most serious complications in orthopaedics and traumatology. The risk factors for these infections are often bacterial resistance to antimicrobials. One of the few solutions available to control bacterial resistance involves antimicrobials, which have a different mechanism of action from traditional antibiotics. Antimicrobial peptides (AMP) appear to be highly promising candidates in the treatment of resistant infections. We have identified several AMP in the venom of various wild bees and designed analogues that show potent antimicrobial activity and low toxicity against eukaryotic cells. The aim of the present study was to test the efficacy of one of those synthetic peptide analogues for the treatment of acute osteomyelitis invoked in laboratory rats. Femoral cavities of 20 laboratory Wistar rats were infected with Staphylococcus aureus. After 1 week, eight rats received an injectable calcium phosphate carrier alone, another eight rats were treated with a calcium phosphate mixed with AMP, and four rats were left without any further treatment. After another week, all rats were euthanized and radiographs were made of both the operated and healthy limbs. The animals with the carrier alone exhibited more severe acute osteomyelitis on radiographs in comparison to the recipients of the calcium phosphate carrier loaded AMP and untreated infected individuals. Based on the results of the above mentioned experiment, it was concluded that when injected directly into the site of femoral acute osteomyelitis, the calcium phosphate carrier mixed with AMP reduced osteomyelitis signs visible on radiographs.

Evaluation of MP4OX for prevention of perioperative hypotension in patients undergoing primary hip arthroplasty with spinal anesthesia: a randomized, double-blind, multicenter study.

BACKGROUND: MP4OX (oxygenated polyethylene glycol-modified hemoglobin) is an oxygen therapeutic agent with potential applications in clinical settings where targeted delivery of oxygen to ischemic tissues is required. The primary goal of this study was to investigate MP4OX for preventing hypotensive episodes. An additional goal was to establish the safety profile of MP4OX in a large surgical population. METHODS: Patients (n = 367) from 18 active study sites in six countries, undergoing elective primary hip arthroplasty with spinal anesthesia, were randomized to receive MP4OX or hydroxyethyl starch 130/0.4. Patients received a 250-ml dose at induction of spinal anesthesia and a second 250-ml dose if the protocol-specified trigger (predefined decrease in systolic blood pressure) was reached. The primary end point was the proportion of patients who developed one or more hypotensive episodes. RESULTS: The proportion of patients with one or more hypotensive episodes was significantly lower (P < 0.0001) in the MP4OX group (66.1%) versus controls receiving hydroxyethyl starch 130/0.4 (90.2%). More MP4OX-treated patients experienced adverse events compared with controls (72.7% vs. 61.4%; P = 0.026). Transient elevations in laboratory values (e.g., alanine aminotransferase, aspartate aminotransferase, lipase, and troponin concentrations) occurred more frequently in the MP4OX group. There were no significant differences in the incidence of serious adverse events or in the composite morbidity and ischemia outcome end points, but nausea and hypertension were reported more often in MP4OX-treated patients. CONCLUSION: MP4OX significantly reduced the incidence of hypotensive episodes in patients undergoing hip arthroplasty, but the adverse event profile does not support use in routine low-risk surgical patients for the indication evaluated in this study.

A double-blind, randomized, multicenter study of MP4OX for treatment of perioperative hypotension in patients undergoing primary hip arthroplasty under spinal anesthesia.

BACKGROUND: MP4OX (oxygenated polyethylene glycol-modified hemoglobin) is a novel oxygen therapeutic agent specifically developed to perfuse and oxygenate tissue at risk for ischemia and hypoxia. In this study, we investigated the ability of MP4OX to treat hypotensive episodes. In addition, the tolerability profile of MP4OX in a large surgical population was established. METHODS: Patients from 21 study sites in 5 countries, scheduled to undergo primary hip arthroplasty under spinal anesthesia, were randomized in a double-blind manner to receive MP4OX or hydroxyethyl starch (HES) solution (Voluven®; HES 130/0.4). Patients received the first 250-mL dose of investigational product when systolic blood pressure decreased to the predefined dosing trigger. A second 250-mL dose was given only if the systolic blood pressure decreased to the same trigger level after administration of the first dose. The primary efficacy outcome was total duration of all hypotensive episodes during surgery and the first 6 hours after skin closure. RESULTS: Of the 474 patients randomized, 405 reached the dosing trigger and received at least 1 dose. The mean total duration of all hypotensive episodes was significantly shorter (P < 0.0001) in the MP4OX group (52.4 ± 71.50 minutes; range, 3-442 minutes) compared with the HES group (137.6 ± 120.21 minutes; range, 5-435 minutes). The overall incidence of adverse events (AEs) in the intent-to-treat population was similar between the MP4OX and HES groups (75.2% vs 73.4%; P = 0.733). Transient increases in laboratory values were reported in more patients in the MP4OX group versus HES controls for aspartate aminotransferase (13.4% vs 7.4%; P = 0.052), alanine aminotransferase (6.9% vs 4.9%; P = 0.409), lipase (9.7% vs 3.6%; P = 0.015), and troponin (8.1% vs 2.0%; P = 0.006). There was no significant difference in the incidence of serious AEs reported (6.4% in MP4OX group vs 3.0% in HES controls; P = 0.106). Certain AEs did occur more frequently in the MP4OX group, including nausea (23.8% vs 14.3%; P = 0.016), bradycardia (14.9% vs 5.9%; P = 0.003), hypertension (8.4% vs 2.5%; P = 0.009), and oliguria (5.9% vs 1.5%; P = 0.019). The composite morbidity and ischemia end points did not reveal any differences between the 2 treatment groups. CONCLUSIONS: Administration of MP4OX achieved the end point of treating perioperative hypotension in patients undergoing primary hip arthroplasty under spinal anesthesia. The study was not powered to demonstrate clinical benefit based on the composite morbidity or ischemia outcomes. Although efficacy end points with sufficient power were met, MP4OX is not being proposed for use in routine surgery where the risk-benefit profile would not be favorable based on the safety profile demonstrated in this study.

Ankle block implemented through two skin punctures.

BACKGROUND: Recently, peripheral nerve blocks have increasingly been used in orthopedic surgery. The foot block is an alternative for anesthesia in cases of forefoot and midfoot operations. We propose a modification of the block technique due to potential difficulties concerning the tibial nerve. MATERIALS AND METHODS: The spatial position of the tibial nerve in the neurovascular bundle, proximal to entering the tarsal tunnel and sural nerve behind lateral malleolus was measured on 60 dissected preparations. Modification of the block technique was proposed. A tibial nerve block was administered by inserting a needle, at an area above the upper edge of the heel bone, tangential to the Achilles tendon. The needle was then withdrawn and redirected to the frontal plane and inserted through the tissue, anterior to the Achilles tendon and laterally behind the lateral malleolus to block the sural nerve. A block of the saphenous nerve superficial and deep peroneal nerves was implemented by needle insertion subcutaneously two centimeters proximal to the crest of the ankle joint. The technique was then evaluated in the clinical part of the study in 84 operative procedures. RESULTS: The tibial nerve is located 21.1 mm +/- 2.1 mm from the medial aspect of the Achilles tendon and 11.6 mm +/- 1.3 mm deep in the neurovascular bundle. The distance from the posterior margin of the lateral malleolus to the sural nerve is 18.3 mm +/- 1.9 mm. We achieved a 93% success rate in implementation of the complete foot block in 84 operations. CONCLUSION: The technique, proposed in the anatomical portion of the study and evaluated in the clinical part, had a similar success rate when compared to techniques published in the literature. Though comparable to currently used techniques, this technique provides easier positioning of a patient and a complete block of the foot can be done with two skin injection sites.

Isolated talonavicular arthrodesis in patients with rheumatoid arthritis of the foot and tibialis posterior tendon dysfunction.

BACKGROUND: The foot is often affected in patients with rheumatoid arthritis. Subtalar joints are involved more frequently than ankle joints. Deformities of subtalar joints often lead to painful flatfoot and valgus deformity of the heel. Major contributors to the early development of foot deformities include talonavicular joint destruction and tibialis posterior tendon dysfunction, mainly due to its rupture. METHODS: Between 2002 and 2005 we performed isolated talonavicular arthrodesis in 26 patients; twenty women and six men. Tibialis posterior tendon dysfunction was diagnosed preoperatively by physical examination and by MRI. Talonavicular fusion was achieved via screws in eight patients, memory staples in twelve patients and a combination of screws and memory staples in six cases. The average duration of immobilization after the surgery was four weeks, followed by rehabilitation. Full weight bearing was allowed two to three months after surgery. RESULTS: The mean age of the group at the time of the surgery was 43.6 years. MRI examination revealed a torn tendon in nine cases with no significant destruction of the talonavicular joint seen on X-rays. Mean of postoperative followup was 4.5 years (3 to 7 years). The mean of AOFAS Hindfoot score improved from 48.2 preoperatively to 88.6 points at the last postoperative followup. Eighteen patients had excellent results (none, mild occasional pain), six patients had moderate pain of the foot and two patients had severe pain in evaluation with the score. Complications included superficial wound infections in two patients and a nonunion developed in one case. CONCLUSIONS: Early isolated talonavicular arthrodesis provides excellent pain relief and prevents further progression of the foot deformities in patients with rheumatoid arthritis and tibialis posterior tendon dysfunction.

Lesser tuberosity is more reliable than bicipital groove when determining orientation of humeral head in primary shoulder arthroplasty.

PURPOSE: The objective of the study was to provide statistical evaluation of position of bone landmarks of proximal humerus in relation to transepicondylar line and find out which one is the most suitable for setup of the head retroversion in case of humeral head destruction. METHODS: We measured 185 dry humeral preparations (92 left, 93 right). Structures of interest on the proximal humerus were marked with pointers of custom made steel frame. Angular relationships between the humeral head axis and medial margin of the greater tuberosity, lateral margin of the lesser tuberosity, bicipital groove, and crest of the greater tuberosity were evaluated with respect to intramedullary axis of the proximal humeral shaft. RESULTS: The angle between the humeral head axis and medial margin of greater tuberosity was 11.5 +/- 9.0 degrees , the angle between the lateral margin of the lesser tuberosity and the axis was 47.5 +/- 7.4 degrees , the angle between the bicipital groove and the axis was 31.6 +/- 8.8 degrees at the level of the humeral head. The angle between the crest of the greater tuberosity and the axis was 26.6 +/- 9.6 degrees in plane of the surgical neck. CONCLUSIONS: We statistically proved that the lateral margin of lesser tuberosity is more reliable than the bicipital groove; medial margin of the greater and transepicondylar line for reconstruction of humeral head retroversion. We suggest that the lesser tuberosity should be used to determine the retroversion, especially in cases when the margin of humeral head was destructed.

Attachments of muscles as landmarks for implantation of shoulder hemiarthoplasty in fractures.

BACKGROUND: The attachments of muscles and the position of the humeral head are important for a good functional outcome of shoulder hemiarthroplasties after displaced fractures of the proximal humerus. Deviations in the attachments and changes in their spatial position with respect to the humeral head during surgical reconstruction change the biomechanics and reduce the range of motion of the should joint postoperatively. METHODS AND RESULTS: We used 198 humerus preparations and using 3-dimensional analysis measured the angular relationships between the humeral head axis and medial margin of the greater tuberosity (11.9 degrees +/- 9.1 degrees ), lateral margin of the lesser tuberosity (48.0 degrees +/- 7.8 degrees ), and the crest of the greater tuberosity (27.1 degrees +/- 9.6 degrees ). CONCLUSION: This study provides average values of the positions of the greater and lesser tuberosities with respect to the humeral head axis. We show that the greater and lesser tuberosities are more reliable than the transepicondylar line for reconstruction of humeral head retroversion. LEVEL OF EVIDENCE: Basic Science.

Hydroxyapatite porous coating and the osteointegration of the total hip replacement.

INTRODUCTION: The main purpose of this study is to evaluate the efficacy of the plasma sprayed, combined porous titanium alloy/HA coating in promoting bony ingrowth and mechanical stabilization of total hip implants. The performance of the titanium alloy/HA type coated hip prostheses and the one of the same shape but without any coating, is compared in this paper. MATERIAL AND METHODS: The implants were manufactured from titanium alloy VT-6 (ASTM F-136). The hip stems utilized in the control group were identical to those subsequently coated. The coating consists of a plasma deposited first layer of porous titanium alloy (TiAl(6)V(4)), similar in composition to the forged substrate and a plasma deposited second layer of over-sprayed hydroxyapatite, Ca(10)(PO(4))6(OH)2. Coating is located in the critical area of the hip stems, where high fixation interface strength is desired, i.e. in the proximal area of the stem where the highest stresses occur. The porous titanium alloy/hydroxyapatite (HA) coated femoral stems were implanted in 50 patients. The results were compared with a control group of 50 patients with the same type of endoprosthesis, but without the porous titanium alloy/HA coating. Both groups of patients were operated on and evaluated by the same orthopedic surgeons with a mean follow up of 11.4 years in the HA group and 10.6 years in the control group. RESULTS: HHS in the control group was preoperatively 35.5 points (range 26-49) and 85.1 points (range 54-100) in the time of the last control. HHS in the HA group was preoperatively 34.1 points (range 27-56) and 94.4 points (range 89-100) in the time of the last control. In 28 cases (56%) of the control group a range of translucencies were obvious. These translucent lines, however, did not appear with any of the patients in the coated implant group except one infection stem migration. CONCLUSION: Experience with the HA-type coated hip implants demonstrates substantially higher degree and quality of osteointegration in the porous titanium alloy/HA type implants.

Role of linezolid in the treatment of resistant gram-positive infections.

Incidence of Gram-positive infections caused by bacteria resistant to commonly used antibiotics has increased in the last decades. Resistant strains appeared later in the Czech Republic, however their number has been increasing and new antibiotics have to be used. The greatest increase of frequency can be seen in infections caused by methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci. Vancomycin-resistant enterococci are usually found in hematooncology patients. Curative use of vancomycin is limited due to a narrow spectrum of activity, nephrotoxicity, and limited penetration into tissues (lung) and cerebrospinal fluid. Linezolid is a good option mainly in infections of skin and soft tissues, and it has an evincible advantage over vancomycin in the treatment of nosocomial pneumonia and surgical-site infections. Oral formulations are favourable allowing switch therapy and earlier discharge from hospital.

Topographic variations of the relationship of the sciatic nerve and the piriformis muscle and its relevance to palsy after total hip arthroplasty.

The aim of this paper was to study the anatomical relationship between the piriformis muscle and the sciatic nerve with regard to the possibility of neurological deficit after THA. The incidence of anatomical variation of both structures is 15-30% in the literature. The authors studied 91 cadavers and found an atypical relationship in 19 cases (20.9%). In this study individual variations were found with the following frequency: The sciatic nerve exits below the piriformis muscle in 79.1% of the cases. The sciatic nerve separates into two divisions above the piriformis, one branch passing through the muscle, the other below it (14.3%). An unsplit nerve passes through the piriformis muscle in 2.2%. The nerve separates into two divisions above the piriformis, one branch exiting above the muscle and passing along its dorsal aspect, the second exiting distally below the muscle in 4.4%. The most common reasons for sciatic nerve injury in surgery of the hip joint are direct injuries, ischemia of the nerve tissue, compression or excessive distraction of the nerve, compression by bone cement, thermal damage during cement polymerization, injury during THA dislocation, compression by hematoma, bone prominence or an implanted acetabular component. According to the presented anatomical study, overstretching of the nerve itself or its branches in the area of the pelvitrochanteric muscles after their release from their origin can be another mechanism. Such overstretching can appear in the presence of some of the aforementioned anatomical variants.